Bolt assembly for firearms



Feb. 27, 1968 v. c. THOMPSON 3,370,372

BOLT ASSEMBLY FOR FIREARMS Filed Aug. 22, 1966 2 Sheets-Sheet 1 FIG. 4 55` 4| 410 Y ATTORNEYS Feb. 27, 1968 v. c. THOMPSON 3,370,372

BOLT ASSEMBLY FOR FIREARMS Filed Aug. 22, 1966 2 Sheets-Shen 2 l N VEN TOR.

VERN C. THOMPSON ATTORNEYS United States Patent Gti-ice 3,37,372 Patented Feb. 27, 1958 3,370,372 BOLT ASSEMBLY FOR FIREARMS Vern C. Thompson, R.R. 3, Mora, Minn. 55051 Filed Aug. 22, 1966, Ser. No. 574,154 Claims. (Cl. 42-16) ABSTRACT 0F THE DISCLOSURE A =bolt assembly for a firearm is provided with radially pivotal locking lugs having spaced apart cam follower surfaces thereon, and a slidable expander member having first and second cam surfaces thereon, the reciprocal movement of said expander member within the bolt assembly causing said cam surfaces to act against said cam follower surfaces so as to pivot the locking lugs in and out of complementary apertures in the receiver portion of the firearm barrel. A spring-biased cartridge extractor is slidably mounted in a bolt assembly and carries two projecting elements on the forward end thereof which act to sequentially release a spent cartridge casing from spring-loaded cartridge rim retaining members on the bolt head and then to expel the cartridge casing from the firearm.

This invention relates to a bolt 4assembly for a firearm and more particularly relates to a bolt locking mechanism using locking lugs which may be pivoted radially outwarldly.

Conventional firearms, such as rifles, typically utilize a bolt mechanism which is reciprocated by manual manipulation or by the bleed-off gases generated fby firing of the cartridge. The movement in sliding the bolt from the cartridge receiving chamber to the cartridge firing chamber typically combines a sliding and rotary action over a great distance to lock the cartridge in place for firing or to eject the spent casing. The rotary action is particularly cumbersome in the reciprocation of the bolt and generally requires separation of the rie or firearm -barrel from the receiving and firing chambers.

The bolt must lbe of such a construction that it provides adequate engagement with the gun barrel or receiving or firing chamber such that it is capable of absorbing the forces generated by gas pressure upon detonation of the cartridge without moving. However, in providing a bolt which locks the cartridge in place in the firing chamber and is easily reciprocated to discharge the spent cartridge casing and receive a new cartridge, several parts are typically used. The parts may clog or Ibecome misaligned or, due to the high degree of sliding -action necessary to manipulate the bolt, incur a high degree of wear and a corresponding short life and, as wear increases, incur poor locking qualities.

With these comments in mind it is to the elimination of these and other disadvantages to which the present invention is directed, along with the inclusion therein of other novel and desirable features.

An object of my invention is to provide a new and improved bolt assembly for firearms of simple and inexpensive construction and operation.

Still -another object of my invention is the provision of a new and improved bolt mechanism which has minimum lost motion necessary to release the bolt from the locked position to retract the bolt to the cartridge receiving position yet which positively locks the cartridge in place in the firing chamber.

A further object of my invention is the provision of a novel bolt mechanism which does not utilize a rotary action and relies only on sliding action and which may be either manually or power operated to reciprocate the bolt between the ring chamber and the receiving chamber.

A still further object of my invention is the provision of a novel bolt mechanism for a firearm which is so constructed that clogging of the parts and wearing of the parts are minimized, thereby greatly increasing the reliability of the firearm as well as the speed available in discharging spent cartridge casings and receiving and placing new cartridges in position.

A still further object of my invention is the provision of an improved bolt mechanism which solidly locks a cartridge in place in the firing chamber and which efficiently ejects the spent cartridge casing, the bolt mechanism being extremely simple in its construction and operation and thereby permitting quick and easy assembly or disassembly lby a person of minimum skill or manual dexterity.

These and other objects and advantages of my invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout `the several views, and in which:

FIG. l is a partial side view of a rie with the location of the major members of my invention shown in position in dotted lines;

FIG. 2 is a partial top view of a rifle showing the position of the major members of my bolt mechanism with a cartridge in the firing chamber and with portions broken away for clarity;

FIG. 3 is a partial sectional view taken along the line 3 3 of FIG. 1 and along the line 3--3 of FIG. 5;

FIG. 4 is a partial sectional view showing the bolt mechanism of my invention in position holding a cartridge in the firing chamber;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 1;

FIG. 6 is a partial sectional View taken lalong the line 6--6 of FIG. 4;

FIG. 7 is a partial longitudinal sectional view showing the cartridge casing ejection member of my bolt mechanism;

FIG. 8 is a longitudinal side view of the locking lug members of my bolt mechanism;

FIG. 9 is a transverse View showing the cartridge rim retaining members of my -bolt mechanism;

FIG. 10 is a transverse sectional view showing the forward portion of my bolt mechanism with the cartridge retaining and ejecting assembly in place, the cross section taken along the line 10-10 of FIG. 12;

FIG. 11 is a partial sectional view taken along the line 11-11 of FIG. 6;

FIG. 12 is a longitudinal view showing the expander and bolt member of my bolt mechanism; and

FIG. 13 is a sectional View taken along the line 13-13 of FIG. 12.

One form of the present invention is shown in the drawings and is described herein.

Referring to FIG. 1, a portion of a rie is indicated lby numeral 20 and includes the bolt mechanism of my invention. The major portions of the rifle are shown in dotted lines and will be referred to only briefly in that the parts, with the exception of the -bolt mechanism, are of conventional design. A trigger 21 is operably connected to link members 22 and 23 to actuate the firing pin 25 in response to manipulation of the trigger. The link members 22 and 23 and the ring pin are shown in dotted lines in that they are encased by the housing 26 of the rifle. A magazine 27 is shown retaining shells or cartridges 28 to be received into the receiving chamber of the rifle. A cartridge 28a is shown in dotted lines in the firing chamber 29 of the rie. The bolt mechanism is shown in outline in dotted lines and is indicated by numeral 30. Firing pin 25 is disposed in bolt mechanism 30, axially aligned therein to engage cartridge 28a re- Y the bolt mechanism. Cartridge 28a is shown in the tiring chamber 29 with the bolt mechanism 30 retaining .the cartridge therein. The bolt mechanism 30 is shown in dotted lines in the retracted position to receive asubsequent cartridge into the receiving chamber 31 for disposition of the cartridge into the 4firing chamber 29 after the spent casing of cartridge 28a has been ejected through aperture 32.

.Referring to FIG. 3, the bolt mechanism 30 of my invention is shown in position to receive a cartridge. The bolt mechanism is positioned at the-rear of rbarrel 35 andabuts an ejector plate 34 which is stationary and positioned at the rear end of the barrel. Housing'or barrel receiving frame 26 receives 'barrel 35 which is securely affixed therein. Conventional means such as bolting mayl be used to aflix the barrel to the barrel mounting frame 26. Ejector plate 34 is affixed to the barrel mounting frame with, for example, a press iit of the cylindrically shaped ejector plate 34 into a mating opening in frame 26. The bolt' mechanism 30 is adapted to slide or reciprocate within barrel 35. The bolt mechanism comprises, in general, an expander member 36 which is mounted in the bolt mechanism forV slidable movement along a longitudinal axis. Locking lug members 37 are mounted in bolt mechanism 3i) and reciprocate with the bolt mechanism along the longitudinal axis of the gun barrel 35 and contact the inner portion of the gun barrel when reciprocating. Locking lugs 37 are adapted to pivot radially outwardly in response to the sliding movement of expander member 36. Firing pin 25 is shown at the longitudinal axis of the bolt mechanism and reciprocates with the bolt mechanism from the cartridge receving chamber'to the cartridge ring chamber. The tiring pin 25 is slidable within the bolt mechanism and response to the trigger 21 through linkage assembly 22 and 23. The forward portion of the bolt mechanism includes a longitudinal opening 39 to receive the firing pin. The position of the bolt mechanism in FIG. 3 corresponds to the dotted line position of the Ibolt mechanism shown in FIG. 2.

In FIG. 4, the 4bolt mechanism is in the position as indicated by the solid lines of FIG. 2 with a cartridge retained therein. The cartridge is indicated by the numerral 28a and the ring pin 25 is shown in position to contact the p'r'imer of the cartridge 28a. In this position, it shouldbe noted that the locking lug members 37 engage apertures 46 in barrel 35 and abut along surfaces 41 thereof which are substantially transverse to the dire-ction of travel of the `bolt mechanism 30, thereby preventing rearward .movement of bolt mechanism 30 -at such times as the locking lug members 37 engage the corresponding apertures 40 in barrel 35. The expander member 36 is shown in position forwardly within the bolt mechanism 30, maintaining locking lug members 37 in the radiallyexpanded position. Firingrpin 25 is in position to contact the pri-mer cap of cartridge 28a responsive to the trigger 21 and link members 22 and 23.

Referring to4 FIG. 8, the locking lug members of my 'boltmechanism are shown separately away from the bolt mechanism. The locking lug members 37 include a pair ofbarrel engaging elements 42 which expand radially outwardly to engage with the barrel, securely locking the bolt mechanism in place with a cartridge in the tiring chamber. The locking' lug members have an inner surface.43 which may be termed an expander camA follower surface. The expander, in its forward movement within the bolt mechanism acts as a cam with the surface 43 as a cam follower, and forces the lug members 37 outwardly so that barrel engaging elements 42 contact the barrel of'the firearm and engage in barrel'apertures 40 with surfaces 4450i the lug members`37- in contact with the corresponding transverse surface 41 of the barrel 35 to maintain the bolt mechanism in position. As the expander member retracts, .a portionof the expander contacts a secondy lug cam follower surface 46 which cams the barrel engaging elements 42 inwardly ink response to` the rearwardy expander movement. Secondv retractor surface 46 is included to aid in quickly urging barrel engaging elements 42 away from the apertures 40-in the barrel 35 as the expander slides to itsrearward position in response to the manual or gas operated slide. Since the locking lugs contact, on their outer surfaces, the barrel of the firearm, a fulcrum point 47 isv provided which forms a pivot point about which the lugmembers' 37 may pivot in response to movement of the expander.

FIG. 12 shows the bolt member indicated specifically by numeral 48 of my bolt mechanism 30 separatefrom` the barrel andwithout the locking lug members placed therein. The bolt member includes expander member 36 which isv slidably mounted within the bolt member fori movement along its longitudinal axis. The expander in-d cludes an aperture 49 along the longitudinal axis to receive the tiring pin 25. An aperture for housing the cartridge ejector member is indicated at Sill` The forwardportion of the bolt member includes a cartridge receiving portion or recess 51 within which a cartridge ejecting and retaining assembly operates to engage the cartridge rim. An opening 52 receives the cartridge rim. The rim retaining and ejecting assembly is not shown in this figure. Aperture 39 receives the firing pin 25 for cont-act with the primer of the shell which is disposed within opening 52. The cartridge ejecting assembly is not shown in this ligure.

The expander member comprises a slide receiving notch 54 to receive a slide (shown at 59 in FIG. 5) which may be manually or gas operated for movement of both the expander and bolt mechanism from the firing chamber position to the receiving chamber position. The expander includes a rst camming surface 55 adapted to cam surface 43 of the locking lug members forcing the locking lugs radially outwardly in response. to forward movement of the expander 36 within bolt member 48. As the expander moves forwardly, the bolt member is stationary for a portion of the over-all longitudinal slide or movement of the slide. As the slide is moved forwardly to place a cartridge in position for firing, the bolt member moves forwardly to a position allowing the locking lug barrel engaging elements 42 to be urged outwardly into barrel apertures 40 adapted to receive the lug elements 42 thereby allowing the surface 55 `to act against cam surface 43 on locking lugs 37, forcing the lug elements 42 into locking relation with the barrel 35. After firing, the slide, which has an actuating portion thereof is placed in slot 54, iirst moves the expander rearwardly with second camming surfaces 56 engaging; surfaces 46 of the locking lug members 37 thereby cam-- ming the locking lugs away from the apertures 40 in the barrel. Guide surface 57 stabilizes the expander in the bolt member. After the expander is returned to the position shown in FIG. 12, the locking lugs have been retracted and the boltmember 48 then moves rearwardly into position to receive another shell. Since the firing pin does not contact the primer until the locking lugs are locked in place, considerable safety of operation thereby results. It should be noted that the bolt member is generally tubular with opposed longitudinal side members 58.

Referring to FIG. 5, the bolt mechanism ofmy invention is viewed, in a transverse view, from the rear. Barrel 35 is shown mounted in barrel mounting frame 26 and a cartridge 28 is shown in the magazine 27. The firing pin is viewed from the rear. Side members 58 of the bolt member are shown and locking lugs 37 are shown in position for slidable movement within the barrel 35. The slide is indicated at 59 for engagement with the eX- pander member 36 and the bolt member 48. The second camming surface 56 of the expander is shown.

FIG. 13 is a sectional View showing the location of side walls 58 of the bolt member 48 and the configuration of the guide surface 57 which is adapted to meet with the locking lugs 37, which are shown in cross-section in FIG. 5. The cartridge ejector shaft passes through aperture 50 for ejecting the spent cartridge casing from the receiving chamber.

A detail of the rim retaining and ejecting assembly for bolt mechanism is shown in FIG. 6 and includes spring bias means 60 disposed in assembly receiving recess 51 and surrounding the rim retaining members 62 and 63. Aperture 39 is shown with tiring pin 25 disposed therein in position to actuate the primer cap of cartridge 28a. The cartridge is securely mounted in bolt member 48 by the rim retaining members 62 and 63 respectively as they are urged inwardly by circumferential spring bias means 60. Opening 52 receives the cartridge 28a. Cartridge ejecting member 64 is attached to shaft 64a which reciprocates in longitudinal aperture 50 of bolt member 48. The ejecting member includes a beveled cam surface 65 adapted to project longitudinally into recess 51, urging the rim retaining members radially outwardly out of engagement with the rim of the cartridge. Surface 66 in the forward position, engages the bottom of the cartridge, tipping the cartridge away from the rim retaining members, thereby releasing the cartridge.

FIG. 7 shows the cartridge ejecting member in the forward position having ejected a spent cartridge. The rim retaining member 63 has been urged downwardly away from the cartridge rim, allowing the cartridge rim to escape or fall from the bolt member and be released. The spring bias means 60 is continuing to urge the rim retaining members radially inwardly to receive and retain a subsequent cartridge. As the ejecting member 64 moves rearwardly, a subsequent cartridge may be received within aperture 52.

FIG. 9 shows the rim retaining members 62 and 63 respectively. Notch 67 is adapted to receive the beveled surface 65 of ejecting member 64 to permit release of a retained cartridge casing by the forward movement of the cartridge ejecting member. FIG 10 is a transverse view which shows the entire assembly for retaining and ejecting a cartridge. Recess 51 is disposed in bolt member 48. Spring 60 surrounds the rim retaining members 62 and 63 urging them radially inwardly into contact with the rim of a cartridge. Cartridge ejecting member 64 with beveled surface 65 and with ejecting surface 66 is also shown. The beveled surface 65 is adapted to cam against surface 67a of the rim retaining member 63, to release a spent cartridge by spreading apart the biased members and pushing the cartridge casing aside. This provides .a large surface area confronting the cartridge casing during the ejection step.

Referring to FIG. l1, the ejecting element 64 is ndicated in position biased away from the cartridge shell. Spring receiving element 68 is mounted in an aperture 68a and aflixed to cartridge ejecting element shaft 64 at notch 68h. Spring means 69 is retained in the opening 68a by block 70. When the bolt mechanism is returned by the slide into position to receive a subsequent cartridge, the ejecting member through shaft 64a which moves slidably in aperture 50, contacts an ejector plate 34 causing the ejector member 64 to move forwardly, compressing spring 69, and ejecting the spent cartridge when shaft 64a contacts ejector plate 34 (shown in FIG. 3). Spring 69 then returns the ejector member into position for the next cycle.

The operation of the bolt mechanism of my invention may be described by referring to the overall operation of receiving a cartridge, firing the cartridge, and ejecting the spent cartridge casing. The cartridge is held in magazine 27, awaiting ring. At the beginning of the cycle, cartridge 28 is urged into chamber 31. The bolt mechanism is disposed rearwardly to provide clearance, allowing cartridge 28 to enter the receiving chamber 31. Slide 59 moves the bolt mechanism 30 forwardly, engaging cartridge 28 in the receiving chamber 31 and moving cartridge 28 forwardly into the firing chamber 29. Simultaneously, the rim of the cartridge is engaged and retained in the bolt mechanism 30 in recess 51 by mating rim retaining members 62 and 63 respectively, In the forward position, locking lugs 37 are urged outwardly and engage the rifle barrel, maintaining cartridge 28a in the firing chamber. After detonation slide 59, which is manually or gas operated, moves rearwardly, rst engaging the expander which cams lugs 37 out of openings 40 in the rifle barrel. This frees bolt mechanism 30 to move rearwardly as urged by the slide 59. The rearward movement of slide 59 forces cam surface 56 of expander 36 against the rear end of bolt member 48, thereby urging bolt member 48 rearwardly. In the rearwardly position, the bolt mechanism engages ejector plate 34 which actuates cartridge ejecting element shaft 64a, forcing the shaft forwardly, thereby urging the cartridge ejecting element 64 into contact with rim retaining members 62 and 63, forcing the rim retaining member 63 out of contact with the cartridge rim and freeing the cartridge. Simultaneously, the surface 66 of the cartridge ejecting element 64 pushes one side of the spent cartridge casing, urging it outwardly through opening 32 in the rifle barrel, thereby ejecting the spent casing. A new cartridge may now be received into the receiving chamber as described above.

From the foregoing it will be seen that I have provided a bolt assembly for firearms which greatly simplifies the cartridge retaining and ejecting mechanism in firearms. The minimum moving parts and the minimum number of springs provides a reliable weapon which is easy to maintain. Further, in that rotary action is eliminated and in that longitudinal movement is minimized, a rearm utilizing the bolt mechanism of my invention may be operated very swiftly. Using the bolt mechanism of my invention, a one piece rie barrel and receiving chamber may be utilized since the bolt mechanism of my invention simply slides within the barrel and does not require any intricate rotary movement during the sliding movement. The bolt mechanism of my invention is useful not only in ries, but may find a high degree of acceptance and usage in machine guns and in hand guns.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of my invention.

What is claimed is: 1. A rearm having a barrel with a receiving chamber and a tiring chamber and said firearm having slide means, tiring means, trigger means operably connected to said firing means and a bolt mechanism slidably mounted in said barrel for reciprocal movement therein from a position rearwardly of said receiving chamber to a position rearwardly of said tiring chamber, in which position said bolt mechanism is adapted to retain a cartridge in position for ring, said bolt mechanism comprising:

an elongate generally tubular bolt member, said bolt member having a longitudinal axial opening therein;

an expander member mounted in said bolt member for longitudinal movement therein independent of the slidable movement of said bolt mechanism and operably associated with said slide means for actuation thereby, said expander member including a rst cam surface at the outer end thereof and a second cam surface spaced inwardly therefrom;

means to receive a cartridge at the rim thereof mounted on said bolt member whereby said cartridge is securely held in said bolt mechanism as said bolt ymechanism reciprocates from a position rearwardly of said receiving chamber to a position rearwardly of vsaid firing chamber; at least one aperture in the wall of said barrel;

at least one lug member shiftably-mounted'in said bolt member and'constructed and arranged for pivotal `movement in a' radial directionywithurespect tothe longitudinal axis of said barrel, said lug member including an outwardly projecting4 lug element and a first cam follower surface adjacent one end thereof Vand a second cam follower surface spaced rearwardly from said firstl cam follower surface, the forward movement of said expander member after Y said bolt member has been reciprocated into said position rearwardly of said firing chamber causing said first cam surface to engage said first cam follower surface, thereby pivoting said lug member radially outwardly and forcing said lug element into said barrel aperture in locking engagement therewith, and the rearward movement of said expander member bringing said second cam surface into engagement with said second cam follower surface whereby said one end of said lug member is pivoted radially inwardly so as to disengage said lug element from said aperture. 2. A firearm as defined in claim 1 wherein: said slide means is directly connected to said expander member; and further including means on said expander member for reciprocating said bolt member rearwardly and forwardly in said barrel as said expander member is actuated by said slide means. 3. A firearm as dened in claim 2 wherein: said second cam surface comprises said means for moving said bolt member rearwardly in said barrel, said second cam surface being so constructed and arranged on said expander member that when it has completely traversed said second cam follower surface so as to pivot said one end of said lug member radially inwardly, it will engage said bolt member and carry said bolt member to said position rearwardly of said receiving chamber, as said expander member is actuated rearwardly. `4. A firearm as defined in claim 1 wherein:

said lug member extends within said bolt member substantially the entire length thereof, and wherein said cludin g z a cartridge casing ejecting element shiftably mounted in said bolt member for longitudinal movement therein;

bias means retaining said ejecting element in a normal position rearwardly of said bolt member;

at least one cartridge rim retaining member on the forward end of said bolt, said rim retaining member being biased radially inwardly towards a normal position in which it engages the rim of a cartridge;

an ejector member on said barrel arranged to contact said ejecting element and urge it forwardly when said bolt member is moved to said position rearwardly of said receiving chamber; and

first and second portions on the forward end of said ejecting element constructed and arranged to sequentially urged said rim retaining member outwardly away from said cartridge and then to engage the bottom of the cartridge and force it out of said bolt member.

References Cited UNITED STATES PATENTS 427,587 5/1890 Mauser 42-25 2,231,978 2/1941 Wesson 42-25 2,370,189 2/1945 Penney 89190 X 2,473,373 6/1949 Howell 42-25 2,585,195 2/1952 Walker 42-25 X 2,606,383 8/1952 Jensen 42--25 2,775,166 12/1956 Janson 42-16 2,803,080 8/1957 Simmons 4225 2,948,195 8/1960 Linder 89-190 X 3,253,513 5/1966 Maillard 89-190 FOREIGN PATENTS 697,445 lO/ 1940 Germany.

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner. 

